Herringbone Finger Grate for Combine Harvester Straw Protection
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Solution Overview
Problem
Conventional tangential flow threshing systems in combine harvesters are rough on straw, leading to broken grain and inefficient separation, as the concave grates with orthogonal bars and wires can cause chaff to reach the grain cleaning apparatus.
Innovation Solution
A grain separating system with a separating cylinder and grate featuring a herringbone pattern of fingers, where adjacent rows are offset in opposite directions relative to the tangential flow direction, reducing the roughness on straw and enhancing grain separation efficiency, and allowing for adjustable finger spacing and pivoting for different crop types and conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional bar and wire grid concave grate is used in a tangential flow threshing system, then the separation function is provided, but the grate is rough on straw causing chaff to reach the grain cleaning apparatus and causing broken grain
Solution Approach 1:
The concave grate is segmented into multiple rows of fingers with alternating orientations. Each row of fingers is angled relative to the tangential direction, with adjacent rows having opposite angles, creating a segmented herringbone pattern that reduces roughness while maintaining separation function.
Solution Approach 2:
The fingers in adjacent rows are oriented at asymmetric angles relative to the tangential direction. Specifically, fingers in one row are angled at +α degrees while fingers in the next row are angled at -α degrees, creating an asymmetric herringbone pattern that reduces straw damage.
2Productivity
If the fingers of the finger grate extend in the tangential direction, then the separation function is optimized, but the straw is damaged and chaff reaches the grain cleaning apparatus
Solution Approach 1:
The fingers are oriented at asymmetric angles to the tangential direction, with adjacent rows having opposite angle orientations. This asymmetric herringbone configuration reduces the roughness on straw while maintaining effective grain separation through the angled finger arrangement.
Data Source
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AI summary
A grain separating system is provided with a separating cylinder having an axis of rotation and tangential directions perpendicular to the axis of rotation. The grate comprises a finger grate having rows of fingers, wherein the fingers of each row are parallel to each other and extend in a direction laterally offset from the local tangential direction of the adjacent separating cylinder. Adjacent rows of fingers are offset in opposite directions from the local tangential direction to create a herringbone pattern.